Heating apparatus



July 7, 1942.

P. s. RUSSEL HEATING APPARATUS Filed May 2, 1939 INVENTOR WKM 4 ATTORNEY F'atented July 7, 1942 HEATING APPARATUS Philip S. Russel, Detroit, Mich., assignor to Detroit Lubricator Company, Detroit, Mich., a

corporation of Michigan Application May 2, 1939, Serial No. 271,330

13 Claims.

My invention relates to new and. useful improvements in heating apparatus and more particularly to a system for controlling the operation of a liquid fuel burner.

An object of my invention isto provide means for controlling the operation of the burner in accordance with the requirement for heat.

Another. object is to provide means to control the supply of air to the burner in accordance with the rate of fuel supplied.

Another object is to provide means to reduce the fan air supply to the burner for intermediate burner operation.

Another object is to render the air supply reducingmeans ineffective upon supply of fuel for full burner operation.

The invention consists in the cooperative arrangement of parts andrthe interrelation of control elements, to be more fully described herein,- after and the novelty of which will be particularly pointed out and distinctly claimed.

In the accompanying drawing, to be taken as a part of this specification, I have fully and clearly illustrated .by invention, in which drawing-- Figure 1 is a diagrammatic view of a heating apparatusembodying the control system of my invention, and

Fig. 2 is a detail view diagrammatically illustrating a modification of certain temperature responsive control means.

Referring to the drawing by characters of reference, I designates generally a heating means such as a furnace or boiler having an outlet flue 2 for the products of combustion and a conduit 3 for supplying the heated medium to a point of use such as a room. Within the combustion chamber there is a burner 4 for liquid fuel which may be of any desired type and which has a supply pipe 5 for liquid fuel leading from a constant level chamber or reservoirfi. The burner 4 is supplied with air by a conduit I having its inlet connected to a motor driven fan or blower 8. In the conduit I there is a damper 9 controlling the discharge of air from the blower 8 to the burner and normally urged to and held in open position by a counterweight I0. An electrically heated thermostatic actuator II for automatically moving the damper 9 toward closed position to reduce the supply of air to the burner 4 is provided. This actuator .II comprises a bimetal warping blade I2 rigidly anchored at one end in a fixed support I3 and having its free end I l engageable with the weight member l0 so that upon warping of blade I2 the damper 9 will be pivoted or turned toward closed position. An

electric resistance element or heater I5-is positioned adjacent or-in heat transfer relation to the blade l2 so that when energized its'heat will warp the blade I2 to operate the damper 9.

The constant level chamber 6 has an outlet I6 which is controlled by a metering valve I'I -provided with a pilot burner slot l8 and having an operating stem I9. Cooperable with the valve I! there is a pair of electrically heated thermostatic actuators 20, 2| operable respectively to move the valve automatically to an intermediate open position to supply fuel for a medium fire and to move the valve to full open position for a high fire or full burner operation. The actuator 20 includes a bimetal warping blade 22 which is rigidly fixed at one end in'a'suppo'rt 23 and which has its free end engageable with a downward facingshoulder 24 formed by a slot in the side of stem 19. The blade 22 is also operable to control an electric switch 25 which may be of the mercury tube type or may be an open contact switch having a thrust member operated movable contact 26. The blade 22 is warped or moved to operate the valve I1 and switch 25 by an electric resistance element or heater 21 positioned closely adjacent or in heat transfer relation to the blade 22. The actuator 2| includes a bimetal blade 28 which is fixed at one end in a support 29 and which has its other end cooperable with a downward facing shoulder 30 formed by the upper end wall of a slot in the stem l9. The blade 28 is also operable to actuatean electric switch 3| which may be of the mercury tube type or may be an open contact switch having a thrust member operated contact member 32. The blade 28 is warped or moved by heat from an electric resistance element orheater 33 positioned closely adjacent or in heat transfer relation to the blade 28.

The operation of the thermostatic actuators and the fan 8 is controlled by a thermostat 34 responsive to the temperature of the medium to be heated by the burner 4 such as air in the room. The thermostat 34 comprises a pair of temperature responsive bimetal elements 35, 36 and which are so related that the element 36 operates at a temperature below the temperature at which element operates. The bimetal element 35 carries a switch contact 31. which is movable by the element into circuit closing engagement with a fixed contact 38 at say 70 F. Secured to the bimetal element v35 there is an armature 39 cooperable with an electromagnet 40 which is operable when energized to separate contact 31 from contact 38 against the force of element 35. The bimetal element 36 carries a contact 4| which is movable into engagement with a fixed contact 42 when the temperature affecting the element 36 drops to say 68 F.

The electric circuits of the heating apparatus are as follows: Line wires 43 and 44 are connected to any suitable source of high voltage supply and lead respectively to the terminals of the primary of a transformer 45. A branch lead wire 44 connects the line wire 44 to one terminal of the motor driven fan 8. From the other line wire 43, a lead wire 46 extends to the movable switch contact 32 and has a branch wire 41 connected to the movable contact 26 of the switch 25. The other terminal of the fan motor is connected by a lead wire 48 to the fixed contacts of switches and 3|. The transformer secondary is connected by a lead wire 49 to the thermostatic switch contact 38 and by a branch wire 50 to the thermostatic switch contact 42. ing from the bimetal element there is a lead wire 5| which connects to the bimetal actuator heater 2'! which is electrically connected to the heater I5 by a lead wire 52. The other side of the transformer secondary is connected by a lead wire 53 to the heater l5. The bimetal element 36 is connected by a lead wire 54 to the coil of the electromagnet which is connected by a lead wire to the lead wire 53. Also, from the element 36 there extends a lead wire 56 which connects to one end of the resistance heater 33 which has its other end connected by a lead wire 57 to the lead wire 53.

The operation of the heating apparatus, as-

suming that the pilot light supplied with fuel through the open upper end of slot I8 is burning in the burner 4, is as follows: If the temperature in the room or space to be heated drops to the predetermined degree, say 70 F., then bimetal element 35 will move switch contact 31 to closed circuit engagement with fixed contact 38. This will complete a circuit from the secondary of transformer 45 through lead wire 49 and lead wire 5| to the electric heater 2?, thence via lead wire 52 to the electric heater l5, and thence via lead wire 53 back to the transformer secondary. The resistance element 21 will now heat the blade 22 which will bend upward and close switch 25 so that the fan 8 will be energized from line 43 through lead wires 46 and 4'! to and through the closed switch 25, and thence via lead wire 48 to and through the motor of fan 8 and through branch wire 44 to the line wire 44. As the fan starts to operate, the continued heating of blade 22 will bring its free end against shoulder 24, so

that on further warping of the blade, the valve H is lifted to an intermediate position to supply oil through pipe 5 for medium fire. Simultaneously with the opening movement of valve H, the blade |2 will be heated by resistance element l5 and move the damper 9 toward closed position to reduce the conduit flow area sufficiently so that the air discharging from the fan 8 to the burner 4 will provide for a proper quantity of air relative to the intermediate supply of fuel to give a proper flame at the burner for medium fire. If the operation of the burner at medium fire is insufficient to maintain or increase the temperature in the room or space so that the temperature further decreases, then when the temperature reaches say 68 F., the responsive element 36 will move contact 4| into engagement with contact 42 to close the circuit for high fire or full burner operation. Closing of this circuit results in opening of the circuit of bimetal element 35 and Leadthe closure of the circuit through the heater element 33. Upon engagement of contacts 4| and 42 the electromagnet 48 will be energized by a circuit from the transformer secondary through lead wire 49, branch wire 50, element 36 and lead wire 54 to the electromagnetic coil and thence via lead wire 55 to lead wire 53 and back to the transformer secondary. Simultaneously with the energization of the electromagnet 40, current will flow through lead wire 56 to the heater 33 and thence via lead wire 51 to lead wire 53 and back to the transformer secondary. The opening of the circuit at contacts 31 and 38 by the electromagnet 40 will deenergize heater element 2! and I5 but before blade 22 cools sufiiciently to open switch 25, the blade 28 will be warped upward to close switch 3|, thereby maintaining continuous operation of the fan 8. The upward warping of blade 28 will also engage its free end with shoulder 30 before blade 22 starts to move downward and therefore as blade 28 continues to warp, the valve will be moved further toward open position from its intermediate position. The deenergization of heater |5 will permit the damper 9 to move toward and finally to full open position by reason of the counterweight H] which is acting against the bimetal blade |2. When the bimetal element 36 becomes satisfied by increase of temperature above 68 F., the circuit will be broken between contacts 4| and 42, thereby deenergizing the electromagnet 4D to permit element 35 to be flexed by its inherent force so that contact will again be made between contacts 3! and 38. This will result in the blade 22 again being heated to warp upwardly to close switch 25 and to position the free end of the blade to receive the shoulder 24 at the intermediate valve open position as the blade 28 cools and moves downward. Simultaneously with the cooling of blade 28 to lower the valve IT to intermediate position, the blade |2 will be heated by heater l5 so that the damper 9 will be moved to a position cutting down the air supply to the burner 4. Upon bimetal element 35 becoming satisfied to open circuit at contacts 3'! and 38, the heater elements 21 and I5 will be deenergized so that blades 22 and 2 respectively will cool, thereby opening the circuit to the fan 8 and closin valve l1 and permitting the damper 9 to move to full open position. The pilot slot [8 will however remain open to provide sufficient fuel to maintain a pilot flame in the burner 4.

In the circuit arrangement shown in Fig. 2, the sequence of operations above described is likewise performed. However, the thermostat 34 is replaced by a single temperature responsive element 58 having a contact 59 cooperable with a fixed contact 60 and also carrying a contact 6| cooperable with a fixed contact 62. The contact 6| is carried by a spring blade 63 and i so positioned relative to contact 62 that upon temperature decrease to say 70 F. the contacts 6| and 62 will engage and then by reason of the lost motion in spring blade 63 the responsive means 58, which is preferably a bimetal blade, can warp further until at say 68 F. the contact member 59 will be moved into engagement with contact member 60. The circuit to lead Wire 5| is in this case controlled by a relay 64 having its movable armatm'e contact 65 connected to the lead wire 5| and normally in contact with the fixed relay contact 66 connected to the fixed contact 62 of the thermostat. The coil of the relay is connected to the lead wire 56 and to the fixed thermostat contact 68 by a lead wire 61.

' engageable with and operable to move said valve toward open position, electrically operable means The. operation of the contral means of Fig; 2 is briefly asifollowsz' When the temperature in the room or space drops to say '70 F., the circuit to the medium fire resistance heater 2] and to the damper resistance element l5 will be coml.

respective of medium fire operation so that atsay 68 F. the bimetal blade 58 moves contact 59 into engagement with contact 60, then the relay 64 will be energized to move contact 65 out of engagement with contact 66, thereby breaking the circuit through lead wire 5| to the heater elements 21 and I5 but simultaneously therewith completing the circuit through lead wire 56 to the heater element 33 for high fire operation.

What I claim and desire to secure by Letters Patent of the United States is:

1. In a heating system having a liquid fuel burner, a valve for controlling the supply of fuel to the burner, electrically controlled means engageable with and operable to move said valve toward open position, temperature responsive;

means, a switch mechanically actuated by said responsive means and operable to close the circuit of said controlled means, electrically controlled means engageable with and operable to move said valve further toward open position, means oper-- able upon occurrence of a temperature decrease adjacent said responsive means to close the circuit of said second-named controlled means, and means dependent upon closure of the circuit of said second-named controlled means to open said switch thereby to deenergize said first-named controlled means.

2. In a heating system having a" liquid'fuel burner, avalve for controlling the supply of fuel to the burner, electrically controlled means en-:

gageable with and operable to'move said valve toward open position, temperature responsive means, a switch mechanically actuated by said responsive means and operable to close the circuit of said controlled means, electrically controlled means engageable with and operable to move said valve further toward open position, means operable upon occurrence of a temperature decrease adjacent said responsive means to close the circuit of said second-named controlled means, and magnetic means energized due to the closure of the circuit of said second-named controlled means and operable to open said switch thereby to break the circuit of said first-named controlled means.

3. In a heating system having a liquid fuel burner, a valve for controlling the supply of fuel to the burner, electrically controlled means .engageable with and operable to move .said'valve toward open position, temperature responsive means operable mechanically to .close' the circuit of said controlled means, electrically controlled means engageable with and operable to .move said valve further toward open position, means operable upon occurrence of a temperature de- :1"

crease adjacent said responsive meansm'echanically to close the circuit of said second-named controlled means, and magnetic means operable to move said responsive means to break the circuit of said first-named controlled means and energized due to the closure of the circuit 'of said second-named controlled means.

4. In a heating system having a liquid fuel burner, a valve for controlling the supply .of fuel to the burner, electrically controlled'means said valve further toward open position, a second temperature responsive means operable upon occurrence of a temperature decrease adjacent said first responsive means to close the circuit of said second-named controlled means, and electrically operable means to deenergize said first-named controlled means and dependent upon closure of' the circuit of said second-named controlled means.

5. In a heating system having a liquid fuel burner, a valve controlling the supply of fuel to the burner, a motor driven fan to supply air to the burner; a normally open damper controlling the air supply to the burner, electrically controlled means to move said damper toward closed position, electricall controlled means to move said valve toward open position and to close the circuit of said fan, a temperature responsive switch operable upon occurrence of a predetermined temperature to close the circuits of said first-namedand said second-named electrically controlledmeans, electrically operated means to move said valve further toward open position, and means operable upon a decrease of temperature below said predetermined temperature to opentlie circuit of said first-named electrically controlled means and to close the circuit of said electrically operated means.

6. In a, heating system having a liquid fuel burner, a valve controlling the supply of fuel to the burner, a motordriven fan to supply air to the burner, .a normally open damper controlling the air supply to the burner, electrically controlled means to move said damper toward closed position, electrically controlled means to move said valve toward open position and to close the circuit of said fan, a temperature responsive switch operable upon occurrence of a predetermined temperature to close the circuits of said first-named and said second-named electrically controlled means, electrically operated means to move said valve further toward open position, electromagnetic means operable to open the circuit of said first-named electrically controlled means, and means operable upon a decrease of temperature below said predetermined temperature to'close the circuits of said electromagnetic means and of said electrically operated means.

7. In a heating system having a liquid fuel .burner, a valve controlling the supply of fuel to the burner, a motor driven fan to supply air to the burner, a damper controlling the air dischargelfrom the fan, means tending to hold said damper in openp'osition, electrically heated thermostatic means to move said damper toward closed position against the force of said holding means, a switch. controlling the circuit of said said thermostatic switch to open position, electrically operated means operable to move said valve further toward open position, a second switch controlling the circuit of said fan and closed by operation of said second-named electrically operated means, and a thermostatic switch operable upon a decrease of temperature below said predetermined temperature to close the circuits of said electromagnetic means and of said second-named electrically operated means.

8. In a heating system having a liquid fuel burner, a valve controlling the supply of fuel to the burner, a motor driven fan to supply air to the burner, a damper controlling the air discharge from the fan. means tending to hold said damper in open position, electrically heated thermostatic means to move said damper toward closed position against the force of said holding means, a switch controlling the circuit of said fan, electrically operated means operable to close said switch and then to move said valve toward open position, a thermostatic switch operable upon occurrence of a predetermined temperature to close the circuit of said electrically operated means and of said electrically heated means, a normally closed switch controlling the circuit of said electrically operated means and of said electrically heated means, electromagnetic means operable to move said normally closed switch to open position, electrically operated means operable to move said valve further toward open position, a second switch controlling the circuit of said fan and closed by operation of said second-named electrically operated means, and a thermostatic switch operable upon a decrease of temperature below said predetermined temperature to close the circuits of said electromagnetic means and of said second-named electrically operated means.

9. In a heating system having a liquid fuel burner, a, valve controlling the supply of fuel to the burner and normally supplying fuel for a low fire, a motor driven fan to supply air to the Burner for medium fire operation, a normally open damper controlling the air supply to the burner, electrically controlled means to move said damper toward closed position to allow sufficient air for medium fire operation, electrically controlled means to move said valve toward open position for flow of sufficient oil for medium fire operation and to close the circuit of said fan, and a temperature responsive switch operable upon occurrence of a predetermined temperature to close the circuits of said first-named and said second-named electrically controlled means.

10. In a heating system, a burner, means to supply air to said burner under pressure, means to supply fuel to said burner, a damper positioned intermediate said air supply means and said burner and operable for controlling the air supply to said burner and normally held in an open position, a valve controlling the fuel supply to said burner, a first electrically energized means positioning said valve in a position for predetermined fuel fiow, a second electrically energized means controlling said damper and operable to urge said damper toward a closed position to provide only sufiicient air for said predetermined fuel flow, a third electricall energized means controlling said valve, means responsive to the temperature change established by said burner and operable to energize said third energized means to move said valve toward open position, and means energized upon operation of said responsive means to deenergize said damper controlling means and said first electrically energized means.

11. In a heating system having a fluid fuel burner, valve means controlling flow of fuel to the burner, a conduit adapted to supply air under natural draft to the burner, fan means for supplying air under pressure through said conduit to the burner, a movable damper positioned in the path of the air supplied by said fan means for obstructing the flow of air to the burner and normally acting to maintain a predetermined minimum obstruction to air flow thereby to allow natural draft fiow through said conduit for low fire burner operation, means responsive to a temperature change established by the burner, actuating means for moving said valve means toward open position to supply a predetermined flow of fuel to the burner and actuated by and operable upon a predetermined low temperature of said responsive means, said actuating means being operable upon actuation to energize said fan means, means operable to urge said damper toward open position, force exerting means for positioning said damper in a partially open position against the force of said urging means to increase the obstruction to air flow thereby to cause a reduced air fiow to be supplied to the burner by said fan means, said valve actuating means being actuated by and operable upon a further reduction of the temperature of said responsive means below said low temperature to move said Valve means further toward open position to suppl a second predetermined flow of fuel to the burner greater than said first-named predetermined flow, said force exerting positioning means being operable by said responsive means at said further temperature reduction of said responsive means to cause said urging means to move said damper into a position to provide a decreased obstruction to air flow thereby to allow a flow of air to the burner greater than said reduced air flow.

12. In a heating system for an enclosed space and having a fluid fuel burner, a valve means controlling fiow of fuel to the burner, a motor operated fan for supplying air to the burner, a damper positioned to obstruct the air flow to the burner, thermostatic means having two switch portions and positioned within the space heated by the burner, said thermostatic means being operable at one predetermined temperature to close one of said switch portions and being operable at a lower predetermined temperature to close the second of said switch portions, a first bimetallic valve actuator engageable with and operable to position said valve means for supplying fuel at a first rate of flow to the burner, an electric heater energized by closure of said one switch portion and operable to cause said first actuator to position said valve means for said first fuel rate, a second bimetallic valve actuator engageable with and operable to position said valve means for supplying fuel at a greater rate of flow to the burner than said first rate of flow, a second electric heater energized by closure of said second switch portion to cause said second actuator to position said valve means for the supplying of said greater fuel flow, means operable to Luge said damper toward open position, a third bimetallic actuator operable to move said damper toward closed position and against the force of said urging means, an electric heater for actuating said third actuator, switch means actuated by said first actuator for energizing said fan prior to the positioning of said valve means by said first actuator for said first rate of flow of fuel to the burner, said lastnamed electric heater being controlled by said thermostatic means to actuate said third actuator to move said damper toward closed position for reduced air flow at said first rate of fuel flow and to position said damper in an open position for increased air flow at said greater rate of fuel flow.

13. In a heating system having a fluid fuel burner, duct means for supplying air to the burner, fan means for supplying air under pressure through said duct means, a damper positioned in the path of and obstructing the flow of air to the burner, means operable to urge said damper toward open position for a first predetermined rate of air flow to the burner, a valve controlling flow of fuel to the burner, means independent of said damper urging means for maintaining said valve in an open position for a first rate of fuel flow to the burner, said first fuel flow rate being so related to said first air flow rate thereby to produce a desired burner flame, a bimetallic actuator operable to move said damper toward closed position against the force exerted by said damper urging means to reduce the rate of air flow to the burner to a second predetermined rate, means responsive to a temperature established by the burner and operable upon a predetermined temperature thereof to cause said actuator to move said damper toward closed position and to cause said valve maintaining means to move said valve toward closed position to supply a second predetermined rate of flow of fuel for a smaller desired burner flame of a desired character.

PHILIP S. RUSSEL. 

